378.17. For the purposes of this subdivision IV.2, the following rules apply:(1) if, at a particular time, substantially all of the residential units in a multiple unit residential complex containing 10 or more residential units are residential units in respect of which the condition mentioned in subparagraph c of paragraph 1 of the definition of “qualifying residential unit” in section 378.4 is satisfied, all of the residential units in the complex are deemed to be residential units in respect of which that condition is satisfied at that time; and
(2) except in the case of residential units referred to in paragraph 1 of the definition of “self-contained residence” in section 378.4,(a) the two residential units that are located in a multiple unit residential complex containing only those two residential units are deemed to together form a single residential unit, and the complex is deemed to be a single unit residential complex and not to be a multiple unit residential complex, and
(b) if a residential unit (in this subparagraph referred to as a “specified unit”) in a building affords direct internal access with or without the use of a key or similar device to another area of the building that is all or part of the living area of another residential unit, the specified unit is deemed to be part of the other residential unit and not to be a separate residential unit.